System related to intravenous anaesthesia

ABSTRACT

The invention shows that conditions can be created in intravenous anaesthesia in which single-patient parts and accessories are separated from multi-patient parts and accessories by utilisation of a filter preventing contaminating particles from migrating from single-patient parts and accessories to multi-patient parts and accessories.

This is a U.S. National Phase Application Under 35 USC 371 and applicantherewith claims the benefit of priority of PCT/SE00/02222 filed Nov. 13,2000, which was published Under PCT Article 21(2) in English andApplication No. 9904123-(8 filed in Sweden on Nov. 15, 1999.

FIELD OF THE INVENTION

The present invention relates to a system in intravenous anaesthesiaand, more particularly, to a system for use in intravenous anaesthesiafor adjustable delivery of fluid medication to a patient to beanaesthetised.

The present invention relates more particularly to a system comprisingat least one container for the said fluid medication, a circuit forregulating the volume of medication supplied to the said patient perunit of time and a tube between the said container and the said patient.

The following description utilises the term “patient”. “Patient” refersboth to a person and to different animals requiring anaesthesia forsurgical procedures.

PRIOR ART

Intravenous administration of a parenteral nutritional support solution,or a liquid comparable to a parenteral nutritional support solution,with a catheter, needle or cannula introduced into a vein, andconnection of a tube between this cannula and a container holding thesaid parenteral solution, such as a saline solution or the like,positioned at a higher level than the patient, are previously known. Inthese applications, the container is normally hung on a stand.

A valve arrangement, through which the volume of fluid can be adjustedwith different settings producing different tube choking, i.e. thevolume of fluid administered per unit of time can be adjusted, isattached to the tube.

Arrangements of this kind are patient-related. This means that thecontainer, tube, valve arrangement etc. which are relativelyinexpensive, are discarded after the fluid has been administered, and nostringent demands are made on the accuracy of the rate of fluidadministration. The pressure of fluid in the tube and cannula willdepend on the height of the fluid container above the level of thepatient.

No extreme demands are made on cleanliness, because the total amount offluid in the container is selected and intended for only one patient andbecause the empty container with its associated valve arrangement andtube is discarded after infusion of the parenteral nutritional supportsolution or the like.

However, when intravenous anaesthesia is involved, greater demands mustbe made on accuracy in the rate of medication infusion, time-relatedvariations in the rate set, the volume delivered and cleanliness.

In intravenous anaesthesia, the field to which the present inventionrelates, an anaesthesia-inducing drug is intravenously supplied to thepatient, usually in large amounts during an initial phase in order toinduce a desired depth of anaesthesia in the patient, followed bysmaller amounts to keep the patient within suitable limits for thedesired depth of anaesthesia.

Medication required for this purpose is supplied in containers holdingstandard volumes, concentrations etc. So estimating the time requiredfor the suitable state of anaesthesia and the desired of anaesthesia andselecting a medication container volume, based on patient-relatedcriteria (age, sex, race, weight etc.), corresponding to the timerequired to perform a surgical procedure, are also known.

However, such estimates have proved to be very rough, as every surgicalprocedure is unique and duration is difficult to determine in advance.

If an operation takes less time than estimated, too much medicationcould be left in the container and tube, i.e. a residual volume, whichmust be discarded. If an operation lasts longer than estimated, an emptymedication container will have to be replaced with a new, fullcontainer.

This replacement of an empty container with a full one is aninconvenient circumstance during a surgical procedure, not the leastbecause of the risk of erroneous connection, and the normal tendency isto start with a container whose volume of medication is excessive,thereby obviously increasing residual volume at the end of the surgicalprocedure.

If the selected volume still proves to be inadequate, the used, emptycontainer must be replaced with a full container. Experience has shownthat the excessive amounts of medication in the new containercontributes to residual volume which must be discarded.

These containers are normally placed in an infusion unit in which thevolume of medication infused per unit of time is regulated, making thereplacement of an empty container with a full one a time-consuming step.

Analgesics and/or muscle relaxants are also commonly used in conjunctionwith the induction of anaesthesia with intravenous infusion of hypnoticsand soporifics.

Containers, tubes etc. are also all devised for use with a singlepatient.

The risk of contamination is deemed to be too great for utilisation ofone medication container with a plurality of patients, as bacteria,viruses and similar particles from a first patient could migrate upthrough the tube into medication in the container and be passed on tosubsequent patients.

Medication contaminated in this way could then be supplied to a second,third, fourth patient etc. through use of the same cannula and/or thesame container.

Different systems and devices for adjustable regulation of theadministration of a fluid anaesthetic to a patient to be anaesthetisedare previously known. An infusion unit pump, which by means of positivepressure in a container (a syringe arrangement), is used here to forcemedication through the tube and a cannula to a patient.

This application makes major demands on highly adjustable and accuratelyregulated administration of medication per unit of time and majordemands on the control of this process, control being dependent upondetectable patient-related criteria.

The simplest embodiment of such a system for intravenous anaesthesiacomprises at least one container for holding the said fluid medication,a circuit for regulating the volume of medication supplied to thepatient per unit of time and a tube, between the said container or thesaid circuit and the said patient, one end of which being attached to acannula inserted into a vein or the like.

The container, with tube and a valve arrangement, is normally conjoinedinto a single unit and can be located in an infusion unit containing apump controlled by a control unit connected to the infusion unit.

This known arrangement is illustrated in greater detail in the followingdescription of the embodiment shown in FIG. 2.

Utilisation of an infusion unit, with an associated control unit, inwhich the control unit is devised to controllably drive a stepper motorconnected to a piston in a syringe on the basis of patient-related andother parameters in order to regulate and evaluate the amount ofmedication supplied per unit of time and the total amount of medicationsupplied, depending on the stepper motor's movements, is previouslyknown.

The invention is therefore primarily devised for use in anaesthesia,more particularly in intravenous anaesthesia.

The present invention accordingly relates to and comprises a systempermitting the infusion of a volume of fluid anaesthetic-inducingmedication per unit of time into the blood of a living creature or apatient.

Here, the use of a lung ventilator and a monitoring and infusion unit,in which the latter, controlled by a control unit, is able to induce adepth of anaesthesia in the patient within limits selected for the depthof anaesthesia, is a practical necessity.

DESCRIPTION OF THE PRESENT INVENTION

Technical Problems

If the circumstance that the technical aspects someone well-versed inthe art needs to consider in solving one or more technical problems istaken into account, insight is initially required into the steps and/orthe sequence of steps which need to be taken and a choice of therequisite means. On the basis thereof, the following technical problemsshould be relevant in achieving the present invention.

With a view to the prior art as described above, creating conditions,using simple means, in which the volume of residual medication remainingafter concluded surgery and conclusion of intravenous anaesthesia iskept to a minimum, largely irrespective of the duration of the state ofanaesthesia, should be regarded as a technical problem.

Creating conditions, using simple means, enabling certain parts andaccessories to be devised for single-patient use and for a smallresidual volume and other parts and accessories to be devised formulti-patient use without migration of contaminating particles fromsingle-patient parts and accessories to multi-patient parts andaccessories, is another technical problem.

Creating, using simple means, a distinct and readily distinguishableinterface between parts and accessories for mufti-patient use and partsand accessories for single-patient use and preventing contaminatingparticles from migrating from the former to the latter should also beregarded as a technical problem.

Here, creating conditions, using simple means, enabling a depletedcontainer for an anaesthesia-inducing drug to be refilled primarily withsmall amounts during the anaesthesia in an effort to keep residualvolume low, especially at the end of anaesthesia, is a technicalproblem.

Being able to realise the importance of creating conditions in thistechnical field enabling a connection arrangement and/or some otherand/or some additional connection arrangement, installed in thedirection of flow, to be devised to prevent small contaminatingparticles from migrating into the said container during a normal flow ofmedication in one direction is a technical problem. The said connectionarrangement is to be positioned so the residual volume is small.

Being able to realise the importance of subdividing a large-volumecontainer into at least two parts, i.e. one part being a container (e.g.a syringe, pump or the like) holding a small volume of medication in theinfusion unit and one part being a reserve container, directly orindirectly connected to the said container, holding a larger volume ofmedication, is a technical problem.

Being able to realise the importance and advantages of providing theinfusion units container with a connector for medication refilling isalso a technical problem. This connection must be located adjacent to orconsist of a container outlet for medication.

Being able to realise the importance and advantages of devising aninfusion unit control unit so it first empties the contents of theinfusion unit container and then transfers small amounts ofanaesthesia-inducing medication to the said container from a reservecontainer, thereby keeping residual volume small, is also a technicalproblem.

Being able to realise the importance of interposing a valve arrangement,comprising e.g. a one-way valve, between the container and the reservecontainer is a technical problem.

Being able to realise the importance and advantages of arranging afilter, using simple means, in or adjacent to the connectionarrangement, to prevent contaminating particles from crossing theinterface between multi-patient parts and accessories and single-patientparts and accessories is also a technical problem.

Creating conditions, using simple means, permitting continuousadministration of medication to the patient, although not by means of acontinuous flow of fluid or medication, is also a technical problem.

Being able to realise the importance and advantages of equipping thesaid filter with a means for shutting off the continuous flow ofmedication is an additional technical problem.

Being able to realise the importance and advantages of arranging afilter, devised to keep bacteria, viruses and similar contaminatingparticles from reaching medication in the reserve container, between acontainer and a reserve container, thereby making possible the use ofmedication in the reserve container as a supplementary volume for usewith a plurality of different people or patients, is an additionaltechnical problem.

Being able to realise the importance and advantages of arranging ashutoff valve between the reserve container and the connectionarrangement is also a technical problem.

Within the scope of the invention, a selected container and/or reservecontainer can consist of a rigid container, or both the container and/orthe reserve container can consist of a flexible container.

Providing the said connection arrangement with a common arrangement fortransferring medication from and sending air to the reserve container,especially when the reserve container is a rigid container, is atechnical problem.

Being able to realise the importance and advantages of having adual-passage filter or connection arrangement, i.e. with one medicationpassage and one air passage separated from each other, a filter forimpeding airborne bacteria, viruses and other contaminating particlesbeing arranged in the air passage, is also a technical problem.

Being able to realise the importance and advantages of using an infusionunit container with a first volume corresponding to the volume requiredduring an initial phase of anaesthesia in order to induce a desireddepth of anaesthesia in the patient is an additional technical problem.After the initial phase, the infusion unit is devised to supply thepatient, with a smaller volume of medication per unit of time in orderto keep the patient within suitable limits for a desired of anaesthesia.

Being able to realise the importance of utilising a three-way connector,connected to the container, the reserve container and patient tube, withone-way valves in a line to the reserve container and tube, a one-wayvalve for the reserve container being devised to permit the passage ofmedication only at a pressure exceeding a pre-selected value somewhatgreater than hydrostatic pressure from the reserve container is anadditional technical problem.

Technical considerations are involved and technical problems must beresolved in realising that a filter must be arranged, upstream and/ordownstream from a one-way filter, and/or that a one-way filter can bearranged upstream and/or downstream from the said filter.

Being able to realise the importance and advantages of conjoining aone-way valve and a filter and locating them close to each other is atechnical problem. An interface can also be arranged between thethree-way connector and the one-way valve. As an alternative, the saidinterface can be arranged upstream from the filter, preferably close tothe reserve container.

Being able to realise the importance and advantages of using an infusionunit container, with a second volume less than a first volume, devisedfor initially inducing a desired depth of anaesthesia in the patient bymeans of a selected number of emptyings and refillings of the saidsecond volume, the infusion unit being devised to deliver a smalleramount of medication per unit of time after the initial phase in orderto keep the patient within suitable limits for the desired depth ofanaesthesia, is a technical problem.

Being able to realise the importance and advantages of connecting thetube to the filter and having the interface downstream and/or downstreamfrom the said filter is a technical problem.

Being able to realise the importance and advantages of having theregulatory circuit consist of e.g. a piston-cylinder arrangement withone-way valves on either side, the reciprocal motion of the piston beingcontrolled by a control circuit in the infusion unit, thereby providingan opportunity for conjoining the said piston-cylinder arrangement andthe said one-way valves in a single unit whose external shape is devisedto fit the shape of a recess for an infusion unit container, a filterbeing provided upstream and/or downstream from the said unit, the saidinterface being provided downstream and/or upstream from the saidfilter, is a technical problem.

Being able to realise the importance and advantages of arranging thetube between a container with a large volume, through one or morefilters and a medication-regulating circuit, and a cannula or the like,is a technical problem.

Being able to realise the importance and advantages of devising the saidcircuit choke off and/or open the tube cross-section, using a plate orsimilar peripheral part of the control unit, in order to regulate thesupply of medication, the said filter being arranged downstream and/orupstream from the said circuit, is a technical problem.

Being able to realise the importance and advantages of devising themedication-regulating circuit to control the supply of medication solelyon the basis of patient-related criteria, the supply of medication beingarranged to be provided from a container above the level of the patient,is a technical problem.

Being able to realise the importance and advantages of devising the saidcircuit to choke off and/or open the tube cross-section by means of apump or a similar peripheral part of the control unit in order toregulate the supply of medication is a technical problem. One or morefilters can then be arranged downstream and/or upstream from the saidpumping unit, an interface being arranged downstream and/or upstreamfrom a filter.

Solution

The present invention is based on a system for adapting theadministration of fluid medication, in intravenous anaesthesia, to apatient to be anaesthetised, the said system thereby comprising at leastone container to hold the said fluid medication, a circuit forregulating the volume of medication delivered to the said patient perunit of time and a tube between the said circuit and/or container to thesaid patient, a connection arrangement being provided between the saidcontainer and the said tube and arranged to enable medication to flowfrom the said circuit and/or container through the said tube to thepatient.

In order to solve one or more of the aforementioned technical problems,the present invention shows that the connection arrangement can consistof a filter devised to separate multi-patient parts and accessories fromsingle-patient parts and accessories, and the said filter forms aninterface preventing contaminating particles from migrating to theformer parts and accessories.

As a further refinement of the invention concept, one connectionarrangement and/or another and/or some additional connection arrangementarranged in the direction of flow is/are devised to prevent the passageof small contaminating particles to the said container during the normalflow of medication in one direction, and the connection arrangement isarranged to keep residual volume small.

With a system of the kind described above, the present invention alsosets forth, as ideas for future lines of development, subdivision of thecontainer into at least two parts, i.e. one part being a container in aninfusion unit and one part being a reserve container connected to thesaid container.

In addition, the present invention shows that the infusion unitcontainer has a medication filler connector located near an outlet orconsists of a medication outlet.

In addition, the present invention shows that the infusion unit'scontrol unit is devised and controllable so it first empties thecontents of the infusion unit container and then sequentially transferssmall amounts of medication from the reserve container, thereby keepingresidual volume small.

The invention also shows that a valve arrangement, comprising at leastone one-way valve, is arranged between the container and the reservecontainer.

In addition, the present invention shows that the said filter, devisedto block the migration of bacteria, viruses and similar contaminatingparticles into medication held in the reserve container, is arrangedbetween the container and the reserve container.

A valve can also be arranged between the reserve container and theconnection arrangement.

The reserve container and/or the container can consist of a rigidcontainer (flask) or, more advantageously, a flexible container (bag).With a rigid container, the said connection arrangement must have anarrangement for sending air to the reserve container.

This shows that the connection arrangement must have two parts, i.e. onepassage for medication and one passage for air, a filter being arrangedin the air passage to block the passage of airborne bacteria, virusesand similar contaminating particles.

The invention sets forth that the infusion unit container shall have afirst volume corresponding to the amount of medication required in orderto induce a desired depth of anaesthesia during an initial phase.

The infusion unit is devised to supply the patient with smaller amountsof medication per unit of time, after the initial phase, in order keepthe patient within appropriate limits for the desired depth ofanaesthesia and achieve small residual volumes.

A three-way connector is connected to the container, reserve containerand patient tube with one-way valves arranged in a line to the reservecontainer and tube.

The reserve container's one-way valve is devised to permit the passageof medication only at a pressure exceeding a pre-selected value, i.e.somewhat higher than hydrostatic pressure from the reserve container.

A filter can advantageously be arranged upstream from the said one-wayvalve, and a one-way valve can advantageously be arranged upstream fromthe said filter.

A shut-off and/or opening valve can be arranged upstream from the saidone-way valve.

A one-way valve and a filter can be interconnected near each other.

Here, the said interface can be arranged between the three-way connectorand the one-way valve.

The said interface can therefore be arranged upstream from the filter,and/or the interface can be arranged next to the reserve container.

A container for an infusion unit can have a second volume, smaller thanthe said first volume, devised for initially inducing a desired depth ofanaesthesia with a selected number of emptyings and refillings of thesaid second volume during an initial phase.

The infusion unit is devised to deliver, after the initial phase, asmaller amount of medication per unit of time to the patient in order tokeep the patient within appropriate limits for the desired depth ofanaesthesia.

Here, the tube can be connected to the filter, and the interface can bearranged downstream and/or upstream from the said filter.

The regulatory circuit can consist of a piston-cylinder arrangement orthe like with a one-way valve on either side, the piston's reciprocalmovement being controlled by a control circuit in an infusion unit.

The said piston-cylinder arrangement and the said one-way valves areconjoined into a physical unit whose external shape can be made to fitexactly into an infusion unit recess intended and devised for acontainer.

The invention also shows that a filter is arranged upstream from thesaid unit, and the said interface is arranged downstream and/or upstreamfrom the said filter.

A tube can be arranged between a container with a large volume, throughone or more filters, past a medication-regulating circuit and a cannulaor the like.

Here, the said circuit is devised to choke off and/or open a section oftube, by the action of a control unit plate or the like on the peripheryof the tube, in order to regulate the supply of medication.

The said filter is arranged downstream and/or upstream from the saidcircuit, and the said interface can be arranged downstream and/orupstream from the said filter.

The medication-regulating circuit is devised to control the delivery ofmedication solely on the basis of patient-related criteria, the deliveryof medication being advantageously arranged for provision from acontainer above the level of the patient.

The said circuit is also devised to choke off and/or open a section oftube, by the action of a pump or a control unit on the periphery of thetube, in order to regulate the supply of medication.

Here, the invention proposes that one or more filters be arrangeddownstream and/or upstream from the said pumping unit.

The said interface can then be arranged downstream and/or upstream fromone or more filters.

The medication-regulating circuit can also be arranged to control thedelivery of medication on the basis of patient-related criteria, thevolume of medication supplied etc., although only taking into accountinformation on the volume of medication supplied per unit of time or thetotal volume supplied.

Even here, the delivery of medication can be devised to take place froma container above the level of the patient.

Advantages

The main advantages of a system according to the invention are that thesystem creates, using simple means, conditions for devising certainparts and accessories for multi-patient use while other parts aredevised for single-patient use through the use of a connectionarrangement, preferably in the form of a filter between them,single-patient parts and accessories being devised for small residualvolumes, thereby limiting undesirable amounts of residualanaesthesia-inducing medication which would have to be thrown out.

This is achieved in practice by use of an infusion unit container whosevolume of medication is devised to be equal to or somewhat less than thevolume likely to be needed for a suitable duration of anaesthesia, adesired depth of anaesthesia and other relevant criteria. If moremedication should be needed, small amounts can be successively suppliedfrom a reserve container, thereby creating conditions for keepingresidual volume small at the end of anaesthesia.

This accordingly reduces the volume of medication which is normallyremoved and thrown out because the infusion unit's volume of medicationis greatly over-dimensioned for safety reasons. A connection arrangementand filter simultaneously prevent contaminated medication from a patientfrom migrating into medication intended for one or more other patients.

The main significant feature in a system for regulating the supply offluid medication to a patient in whom narcosis is to be induced by meansof intravenous anaesthesia is set forth in the characterising part ofpatent claim 1.

BRIEF DESCRIPTION OF THE FIGURES

Two previously known systems for intravenous administration of fluidsand medication to a patient, as well as a system set forth in theinvention, will now be described in greater detail, referring to theattached drawings in which:

FIG. 1 illustrates the principle for intravenous administration of aparenteral nutritional support solution to a patient from a container inwhich the fluid can consist of e.g. a saline solution;

FIG. 2 shows the principle parts of an infusion system for adjustableadministration of medication to a person in intravenous anaesthesia;

FIG. 3 illustrates the principles of a first embodiment according to theinvention;

FIG. 4 shows a longitudinal section of a proposed connection arrangementwith a filter for a medication passage and an air passage;

FIG. 5 illustrates the principles of a second embodiment according tothe invention;

FIG. 6 illustrates the principles of a third embodiment according to theinvention;

FIG. 7 illustrates the principles of a fourth embodiment according tothe invention;

FIG. 8 illustrates the principles of a fifth embodiment according to theinvention;

FIG. 9 is a time diagram illustrating variations in the amount ofmedication administered during anaesthesia.

DESCRIPTION OF PRIOR ART

FIG. 1 is a drawing of a system for adjustable, limited-precisionregulation of a parenteral nutritional support liquid, such as a salinesolution, for intravenous administration to a person.

FIG. 1 shows a cannula 1 inserted into a vein 2 in an arm 3.

The cannula 1 is connected to a tube 4, one end 4 a of which isconnected to the said cannula 1 and the other end 4 b is connected to acontainer 5, usually a flexible plastic container holding a fluid 6,e.g. a saline solution.

Here, a valve arrangement 7 is attached to or arranged around the tube4, and the volume of fluid administered per unit of time can beregulated by the action of the valve arrangement 7 in the known manner.

It should be noted that no great accuracy is needed in theadministration of fluid for this application. So a simple valvearrangement 7 can therefore be used when the amount of fluidadministered per unit of time is not critical.

In addition, large flows, e.g. up to 500 ml/hour or even more in someinstances, can be delivered with this valve arrangement.

A system for regulating the amount of fluid medication administered to apatient to be anaesthetised requires far greater precision.

The process entails initially administering a large flow and thengreatly reducing the flow to an adjustable level, thereby achieving adesired depth of anaesthesia. This is illustrated in FIG. 9.

FIG. 2 is a schematic rendition of a syringe 11 with a container 12, apiston 13 and a control unit 14, containing a stepper motor 15, in aninfusion unit 10.

The system according to FIG. 2 comprises at least one container 12 forfluid medication 16 and a regulatory circuit or control unit 14 forregulating administration of a volume of medication per unit of time tothe said person.

In addition, a tube 4 is arranged between the said container 12 and thesaid patient P.

A connection arrangement 17 between the said container 12 and the saidtube 4 is arranged to enable medication 16 to flow from the saidcontainer 12, via the said control unit 14 and the said tube 4, to thepatient P.

FIG. 2 shows that one tube end 4 a is connected to a three-way connectoror the equivalent to enable one or more containers 11, 11′ to beconnected to the tube 4′, one end of which is arranged for connection tothe cannula 1.

DESCRIPTION OF PROPOSED EMBODIMENTS

The invention is based on the experience that users commonly select amuch larger volume of medication 16 than the volume consumed duringanaesthesia to avoid the need to replace an empty syringe 11 with a newone or refill an empty syringe with medication during surgery.

So large residual volumes remain and cannot be saved for use withanother patient due to the risk of infection.

The invention is based on a system for regulated adaptation of the fluidmedication administered to a patient to be anaesthetised duringintravenous anaesthesia, the said system comprising at least onecontainer to hold the said fluid medication, a regulatory circuit orcontrol unit for regulating the volume of medication administered perunit of time and a tube between the said circuit or container and thesaid patient, a connection arrangement being provided to permit thepassage of medication from the said container to the patient.

A filter, linked to the connection arrangement, is devised to separatemulti-patient parts and accessories from single-patient parts andaccessories. The said filter forms an interface preventing contaminatingparticles from migrating to the former parts and accessories.

This means that the volume of medication 16 can be somewhat less, by awide margin, than the volume calculated as necessary for inducinganaesthesia, and a supplementary volume of medication can be sent to thesyringe 11 from a reserve container 11 a.

The container 1 a and the reserve container 11 b interact by means of aconnection arrangement 31 which could contain valves (V1, V2) and afilter (F1).

The said connection arrangement 31 and/or some other and/or someadditional connection arrangement with filters, arranged in thedirection of flow, is devised to prevent the migration of smallcontaminating particles to the said container 11 b and/or container 11 aduring a normal flow of medication through the tube 4 in a givendirection. The connection arrangement is arranged to ensure thatresidual volume is small.

FIG. 3 shows that the container 11 is divided into at least two parts 11a, 11 b, one being a container or syringe 11 a, holding a selected smallvolume of medication, in an infusion unit 10 and one being a reservecontainer 11 b, holding a large volume of medication, connected to thesaid container 11 a.

Here, the volume of medication for the container 11 a can be selectedfor reasons other than the estimated duration of the surgical procedureand be much smaller, as a sufficient reserve volume is available in thereserve container 11 b.

The invention sets forth the use of one or more filters F, andthis/these filter(s) separate(s) multi-patient parts and accessories Afrom single-patient parts and accessories B.

The filter F forms an interface C preventing contaminating particlesfrom migrating from single-patient parts B to multi-patient parts A.

Single patient parts and accessories B are devised to have a smallresidual volume at the end of anaesthesia. This means that e.g. thecontainer 11 a should then be virtually empty. Other parts andaccessories are selected for a small residual volume.

FIG. 3 is a schematic depiction of a first embodiment with the featuresassociated with the present invention.

The infusion unit's 10 container 11 a has a connector 11 b′ throughwhich medication can be filled, and the connector is arranged close toor consists of a medication outlet 11 a′.

An infusion unit's 10 control unit 14 can be devised to empty thecontents of the infusion unit's container 11 a and then transfer smallamounts of anaesthesia-inducing medication, as needed and successively,from the reserve container 11 b to keep residual volume small insingle-patient parts.

This can be achieved when a piston 13 performs reciprocal movementswithin the dashed range shown in FIG. 3 in order to pump medication fromthe container 11 b to the container 11 a and from the container 11 a,via a three-way connector 37 of the connection arrangement 31 and thetube 4, to the patient.

The anaesthesia can now be concluded with a small residual volumebecause the container 11 a is empty, and tubing has a smallcross-section.

A number of valve arrangements V, each of which containing a one-wayvalve, is arranged between the container 11 a and the reserve container11 b.

A first one-way valve V1 is built into or connected close to thethree-way connector 37, and a second one-way valve V2 is built into orclose to the three-way connector 37 path to the reserve container 11 b.

The one-way valve V2 is connected to a first filter F1.

As an alternative, a filter F2 and a one-way valve V3 can be connectedclose to the reserve container 11 b.

The filter F1 and one-way valve V2 can be omitted in certainapplications. The selected interface is then moved to the positiondesignated C1.

The filter F1 and/or the filter F2 are designed to block the access ofbacteria, viruses and similar contaminating particles to medication 16 ain the reserve container 11 b.

The reserve container 11 b and/or the container 11 a can advantageouslybe flexible or rigid containers.

When a rigid container 11 b is utilised, an arrangement is proposed forfeeding air into the reserve container 11 b as it empties of medication16 a.

There is nothing to prevent having an outlet for medication and an inletfor air.

FIG. 4 shows that a combined arrangement of this kind can be dividedinto two parts, i.e. with a passage 43 for medication and a passage 44for air, and a filter 45 is arranged in the air passage to preventbacteria, viruses and similar contaminating particles from passing fromambient air into the container 11 b.

The medication passage 43 has an upper space 43 a filled with medication16 a. This medication passes through a filtering unit 43 b and, via adrip nozzle 43 c in which drops traverse a gas-filled (air-filled) space43 d to a space 43 e before passing through some additional filter F3 ora valve.

FIG. 3 also shows the use of an infusion unit's 10 container 11 a with afirst large volume 11 a intended for rapidly inducing a desired depth ofanaesthesia in an initial phase.

The infusion unit is also devised to deliver smaller amounts ofmedication per unit of time, after the initial stage, in order keep thepatient within appropriate limits for the desired depth of anaesthesia.

Here, it should be noted that the amount of hypnotic proposed foradministration during the initial phase t0 to t1 can be 10 to 30 mladministered over 3 to 4 minutes, e.g. 20 ml over 2 minutes. The amountsupplied during the remaining time t1 to t2 can be 50 to 100 ml/hour.The total volume administered during the anaesthesia can be 100 to 500ml.

Here, it should be noted that the amount of analgesic proposed foradministration during the initial phase t0 to t1 can be 1 to 2 ml. Theamount administered during the remaining time can be 10 to 50 ml/hour.

Here, it should be noted that the amount of muscle relaxant proposed foradministration during the initial phase t0 to t1 can be 3 to 5 ml. Theamount administered during the remaining time can be 3 to 5 ml/hour.

It should be noted that each of the aforesaid agents requires a separateinfusion unit and control unit.

Hypnotics can be advantageously administered sequentially. Long-actinganalgesics can also be advantageously administered sequentially, whereasmuscle relaxants can be administered continuously under controlledconditions.

A three-way connector 37 is connected to the container 11 a, the reservecontainer 11 b and the patient tube 4 by one-way valves in the line tothe reserve container 11 b and the tube 4. One or more filters can bebuilt into the three-way connector 37.

The one-way valve (V2) for the reserve container 11 b is devised toallow the passage of medication 16 a only at a pressure, exceeding apre-selected value, somewhat higher than hydrostatic pressure from thereserve container 11 b.

A filter F1 is arranged upstream somewhat from the said one-way valveV2, and an additional one-way valve V3 is arranged upstream from thesaid filter F1.

A shut-off and/or opening valve (not shown) can be arranged upstreamfrom the said one-way valve V3.

A one-way valve V2 (V3) and a filter F1 (F2) can advantageously beinterconnected close to one another and form a single unit.

The interface C can advantageously be arranged between the three-wayconnector 31 and the one-way valve V2, but there is nothing to preventarrangement of the interface upstream from the filter F1 and/or close tothe reserve container 11 b.

FIG. 5 shows an alternative to FIG. 3 in which the infusion unit's 10container 11 a′ has a second volume E2, much smaller than the firstvolume E1, the former being devised to deliver a desired depth ofanaesthesia in the patient with a selected number of emptyings andfillings of the said second volume E2 during an initial phase.

It is proposed that the volume E2 be selected so 2–5 emptyings areneeded for the delivery of a sufficient volume of medication during theinitial phase.

The infusion unit is also devised to supply the patient, after theinitial phase, with a smaller amount of medication per unit of time inorder to keep the patient within appropriate limits for the desireddepth of anaesthesia.

FIG. 6 shows an alternative embodiment in which the container 11 a hasbeen removed and medication is only supplied from one large container 11b.

Here, the tube 4 is connected to a filter F4 and/or F5, and one or moreinterfaces C2, C3, C4, C5 can be arranged downstream and/or upstreamfrom the said filter.

Here, the regulatory circuit or control unit 14 consists of apiston-cylinder arrangement 61 with one-way valves V4, V5 on each side,the reciprocal movements of the piston being controlled by a controlcircuit 14 in the infusion unit.

The said piston-cylinder arrangement 61 and the said one-way valves V4,V5 are conjoined into a single unit 62 whose external shape fits theshape of an infusion unit recess devised to hold a container 11 a.

Having the filter F4 arranged upstream from the said unit 62 may beimportant.

The said interface C2, C3 is arranged downstream and/or upstream fromthe said filter F4.

The embodiment according to FIG. 7 shows that a single tube 4 isarranged between a large-volume container 11 b, through one or morefilters F6 and F7 respectively, a medication-regulating circuit 71 and acannula or the like.

The said circuit 71 is devised to choke off and/or open the tubecross-section, by means of a plate 71 a or the like, a stop 71 b and acontrol unit's 14 stepper motor 15, in order to regulate the delivery ofmedication.

The said filters F6, F7 are arranged downstream and/or upstream from thesaid circuit, and one or more interfaces C6, C7, C8, C9 are arrangeddownstream and/or upstream from the said filters F6, F7.

The medication-regulating circuit or control circuit 14 is devised tocontrol the delivery of medication solely on the basis ofpatient-related criteria. The amount of medication delivered and/orvolume per unit of time can be estimated in order to provide the surgeonwith useful information but is not part of the control process. Theseamounts can be obtained from the control unit and the setting set forthe stepper motor.

Patient-related criteria and the choice of same can be made in themanner shown and described in Swedish patent application no. 9901688-(3,filed on 10 May 1999 and entitled “Arrangemang for att kunna tilidela enlevande varelse ett anestesialt tillst{dot over (a)}nd” (i.e.Arrangement for inducing a state of anaesthesia in a living creature).

The contents of the said patent application shall be regarded as a partof this application.

Here, the administration of medication shall be devised to take placefrom a container 11 b above the level of the patient.

FIG. 8 shows that the control unit 14 causes a medication-regulatingcircuit 14 with a stepper motor 15 to choke off and/or open thecross-section of a tube 4 by means of a pump (with a peristaltic actionto force fluid or medication downstream) or similar unit 81 on theperiphery of the tube in order to thereby regulate the delivery ofmedication. A moving means 81 a, acting against a fixed plate 81 b, isarranged here.

Filters F8, F9 are arranged downstream and/or upstream from the saidpumping unit 81, and the said interfaces, such as C10, C11, C12, C13,can be arranged downstream and/or upstream from the filter F8 and F9respectively.

The medication-regulating circuit is primarily arranged for regulatingthe delivery of medication according to patient-related criteria andfrom information on the momentary amount of medication supplied per unitof time.

FIG. 9 shows, using a solid line, that a relatively large volume ofmedication is supplied during an initial phase t0 to t1 in order toquickly induce a state of anaesthesia in the patient. The desired depthof anaesthesia is illustrated with a dashed line.

A relatively small, regulated amount of anaesthesia-inducing medicationis given to the patient for a brief period of time t1–t2 in order tokeep the patient at the desired depth of anaesthesia or for controlledregulation of the depth of anaesthesia.

The possibility of supplying medication in an amount and at a rateconsistent with empirical values while using values for patient criteriafor regulating the period from t1 to t2 also falls within the scope ofthe invention.

The “successive” administration of medication or agents means that anempty container (11 a) is refilled with a given amount (1/2). Thisamount is emptied and then refilled to a lesser degree (114) etc.

The invention is clearly not limited to the exemplary embodiments abovebut can be modified within the scope of the invention concept asillustrated in the following patent claims.

1. A system for controllably regulating the administration of fluidmedication to a patient to be anaesthetised with intravenousanaesthesia, said system comprising an infusion container for holdingand introducing the fluid medication to a single patient, said infusioncontainer including a connector positioned proximate an outlet of saidinfusion container through which said infusion container can be filledwith, and emptied of, the fluid medication, a reserve container forcontaining a portion of the fluid medication that can be transferred tosaid infusion container, said reserve container being useable withmultiple patients, a control unit including a circuit for regulating thevolume of medication delivered from the infusion container to saidpatient per unit of time, said control unit operates to empty the fluidmedication from said infusion container and transfer small amounts offluid medication from said reserve container to said infusion container,a tube between said circuit or said infusion container and said patient,a connection arrangement provided to allow the passage of the fluidmedication from said infusion container to the patient and from saidreserve container to said infusion container, said connectionarrangement comprising a first filter, a first one-way valve positionedbetween said tube and said first filter and a second valve, and a secondfilter positioned upstream of said connection arrangement between saidconnection arrangement and said reserve container, at least said firstfilter and first valve being positioned to separate multi-patient partsincluding said reserve container from single-patient parts includingsaid infusion container and form an interface preventing contaminatingparticles from migrating into at least the reserve container.
 2. Thesystem according to claim 1, wherein the reserve container is connectedor adjacent to said infusion container.
 3. The system according to claim1, wherein the reserve container is a rigid container.
 4. The systemaccording to claim 1, wherein the reserve container is a flexiblecontainer.
 5. The system according to claim 3, wherein said connectionarrangement has an arrangement for sending air to the reserve container.6. The system according to claim 3, wherein the reserve container isdivided into two parts including a medication passage and an airpassage, and wherein a filter devised to block airborne bacteria,viruses and similar contaminating particles is arranged in the airpassage.
 7. The system according to claim 1, wherein infusion containerhas a first volume selected to correspond to the volume of medicationneeded during an initial phase for inducing a desired depth ofanaesthesia in the patient.
 8. The system according to claim 7, whereinthe infusion unit is devised to deliver, after the initial phase,smaller amounts of medication per unit time from the infusion containerin order to keep the patient within suitable limits for the depth ofanaesthesia.
 9. The system according to claim 7, wherein said connectionarrangement comprises a three-way connector that is connected to theinfusion container, reserve container and patient tube.
 10. The systemaccording to claim 9, wherein said one-way valve is devised to permitthe passage of medication only at a pressure exceeding a pre-selectedvalue that is greater than hydrostatic pressure from the reservecontainer.
 11. The system according to claim 1, wherein said firstfilter is arranged upstream from said one-way valve.
 12. The systemaccording to claim 1, wherein said one-way valve is arranged upstreamfrom said filter.
 13. The system according to claim 12, wherein saidsecond valve is a shut-off and/or opening valve located upstream fromsaid one-way valve.
 14. The system according to claim 1, wherein saidone-way valve and first filter are conjoined or located near each other.15. The system according to claim 1, wherein said connector includes athree-way connector, and said interface is arranged between thethree-way connector and the one-way valve.
 16. The system according toclaim 1, wherein said interface is arranged upstream from said secondfilter.
 17. The system according to claim 1, wherein said interface isarranged next to the reserve container.
 18. The system according toclaim 1, wherein said infusion container has a second volume, smallerthan a first volume, for initially inducing a desired depth ofanaesthesia in a patient, by employing a selected number of emptyingsand fillings of said second volume during an initial phase in order toinduce a desired depth of anaesthesia in a patient.
 19. The systemaccording to claim 18, wherein the infusion unit is devised to deliver,after the initial phase, a smaller amount of medication per unit of timein order to keep the patient within suitable limits for the desireddepth of anaesthesia.
 20. The system according to claim 1, wherein thetube is connected to one of said filters, and the interface is arrangeddownstream or upstream from said one of said filters.
 21. The systemaccording to claim 1, wherein the control unit comprises apiston-cylinder arrangement with a one-way valve on each side thereof,and the reciprocal movements of said piston are controlled by a controlcircuit.
 22. The system according to claim 21, wherein saidpiston-cylinder arrangement and said one-way valves on either side ofsaid piston-cylinder arrangement are conjoined in a single unit whoseexternal shape fits the shape of an infusion unit recess devised forsaid infusion container.
 23. The system according to claim 21, whereinat least one filter is arranged upstream or downstream from said singleunit.
 24. The system according to claim 23, wherein said interface isarranged downstream or upstream from one of said filters.
 25. The systemaccording to claim 1, wherein the tube is arranged between said reservecontainer, through at least one of said filters and said medicationregulating circuit, and a member for inserting within the patient. 26.The system according to claim 25, wherein said control unit includes achoking member, and said circuit is devised to have the control unitchoke off and/or open a section of tube, in order to regulate theadministration of medication.
 27. The system according to claim 25,wherein at least one of said filters is arranged downstream or upstreamfrom said circuit.
 28. The system according to claim 1, wherein saidinterface is arranged downstream or upstream from said second filter.29. The system according to claim 25, wherein the medication-regulatingcircuit is devised to control the administration of medication solely onthe basis of patient-related criteria.
 30. The system according to claim26, wherein the infusion unit is positioned above the patient during usesuch that the administration of medication is arranged to take placefrom the infusion container located above the level of the patient. 31.The system according to claim 25, wherein said control unit includes achoking member, and said circuit is devised to have the choking memberof said control unit choke off and/or open a section of tube in order toregulate the administration of medication.
 32. The system according toclaim 31, wherein at least one of said filters is arranged downstream orupstream from said choking member.
 33. The system according to claim 31,wherein an interface is arranged downstream or upstream from said secondfilter.
 34. The system according to claim 31, wherein the medicationregulating circuit is arranged to control the administration ofmedication on the basis of patient-related criteria including on thebasis of information on the volume of medication supplied per unit oftime.
 35. The system according to claim 31, wherein the infusion unit ispositioned above the patient during use such that the administration ofmedication is arranged to take place from the infusion container locatedabove the level of the patient.